For the past year we have attempted to characterize more completely the cognitive impairments in schizophrenia. We have also begun work on the mechanisms accounting for failures in memory in schizophrenia. Patients difficulties do not appear to be due to qualitative abnormalities in susceptibility to interference, encoding, or false memory problems. We have begun to comnputationally model the episodic memory impairments in schizophrenia in order to determine if they are due to general noise or a single stage in mnemonic processing. We have examined disorganized speech in schizophrenia using various semantic processing paradigms. In general patients have difficulties not with the size of their lexicon but rather how they access it automatically, as evidenced in priming paradigms. Thus, we have devised a battery of novel experimental tasks to assess whether schizophrenic patients show a dissociation between lexical integrity and semantic abnormality. This study utilizes patients with schizophrenia, patients with Alzheimers disease and children to find dissociations between the size of the verbal lexicon and its organization. If this is the case then it has important implications for normal cognitive architecture. We have also found using both a nonverbal morphing task and a reaction time task that patients do not have undue difficulty with understanding what an entity is, it is their ability to understand the relations between things that is abnormal. Finally, a genetic study of schizophrenia with an emphasis on intermediate phenotypes is ongoing. We are using a large battery of neurocognitive measures to characterize this intermediate phenotype. We base this on the rationale that patients do not inherit schizophrenia but a variety of susceptibilities to cognitive impairments and their attendant neurophysiologic abnormalities. We will use extreme discordant pairs (affected unaffected) and affected sib pairs for selected variables and attempt to find linkage between cognitive variables and genetic markers. We have already found that some cognitive measures yield high relative risks that are not redundant with diagnosis. - cognition, schizophrenia, neuropsychology - Human Subjects: Interview, Questionaires, or Surveys Only